Consider a tetragonal phase of which the lattice parameters satisfy c = 2a. Diffusivities of the phase were measured in two different directions as:

Question

6.0x10-12 cm2/sec along [101] and 8.0x10-12 cm2/sec along [001].

(a) Determine the diffusivity tensor (Dij) expressed with respect to the coordinate system consisting of crystallographic axes [100], [010] and [001].

(b) Calculate the diffusivity along [201].